A federal judge has ordered North Dakota to stop construction on part of a $2 billion flood control project along the Red River -- a project Minnesota hasn't signed off on yet.

U.S. District Judge John Tunheim issued a temporary injunction Wednesday to halt construction of a ring levee around three small North Dakota towns just south of flood-prone Fargo.

Diversion opponents argued that North Dakota shouldn't start building until Minnesota gives its blessing. Part of the $1.8 billion Fargo-Moorhead Diversion plan includes stretching a flood-control dam across the Red -- a dam that would keep Fargo dry by backing floodwaters onto stretches of Minnesota and North Dakota instead.

The Minnesota Department of Natural Resources is conducting a detailed environmental review, and had asked North Dakota to hold off on construction until that review is complete in August. But North Dakota broke ground last summer, countering that it should be free to build on its own land, using its own money.

On Wednesday, the federal judge sided with Minnesota, which had joined the ongoing lawsuit against the project as a friend of the court. The public costs of delaying construction "are relatively minor," he wrote, compared to the risk of running roughshod over Minnesota's environmental review process.

“The law simply requires that all federal and state environmental reviews be completed before construction begins,” Tunheim wrote. “Construction of the...ring levee violates this principle and creates the real risk of a ‘steam roller’ effect. When considering a project of this size, scope, and potential environmental impact, the review process must be completed first.”

DNR Commissioner Tom Landwehr welcomed the ruling. When the draft report comes out at the end of summer, it will be followed by a public comment period before Landwehr determines whether Minnesota will grant the permits to allow the diversion project to move forward.

"We can hopefully now go back to the orderly process of environmental review and wait for that to play out," he said. "It's a very complicated project that has lots of benefits and impacts. We just have to take the time that we need to think it through, take a hard look, make sure we get it right. That's all we're asking for."

The Fargo-Moorhead Diversion Authority was weeks away from awarding the contract for this year's work on the Oxbow-Bakke-Hickson levee, said the group's chairman, Darrell Vanyo.

"You get a ruling, you're at the mercy of the courts," said Vanyo, who argues that the four-year levee project would not only have protected the cities from diverted floodwater, but would save residents from higher insurance rates when the Federal Emergency Management Agency re-draws the region's flood map in five years.

For now, Vanyo said the authority is trying to figure out whether the injunction halts all work, or whether their crews can continue non-levee improvements inside the city of Oxbow, where the authority is rebuilding a golf course disrupted by the new ring dike.

Gerald Von Korff, attorney for the Richland-Wilkin Joint Powers Authority -- the upstream residents and communities who brought the lawsuit against the diversion project -- said he hopes the ruling will open the doors to negotiations with the diversion authority. Oxbow and its neighbors are mainly at risk of a flood if the diversion project goes through, he said, but Fargo faces the real threat of a serious flood almost every year.

"What we're really looking for is not a win [for his side], but a win-win" for both sides in the dispute, he said. "Our goal was to try to sit down with Fargo and come up with a solution that protects Fargo -- because Fargo deserves protection -- [but] keeps us dry too."

Fargo has been hit by floods in 49 of the past 111 years. Maybe, Von Korff said, all the work on the ring dike around Oxbow could be diverted to flood control projects around Fargo instead.

"My client would like them to move that equipment down to Fargo and start working on flood protection for Fargo," he said. The $70 million price tag for the ring dike, he said, "would be better spent right now in the places that have a natural, real flood problem."

The current plans for the Red River diversion call for a 36-mile channel around Fargo to steer floodwater around the city, instead of over it. A flood control dam across the north-flowing Red would block the rest of the floodwater and back it up onto the fields, farms and a handful of small communities to the south, on both sides of the river. That dam is the sticking point for the DNR, which is taking a hard look at the impact of Fargo's floodwater backing up onto Minnesota land that currently sits high above the flood plain.